OGJ Senior Staff Writer
HOUSTON, Aug. 18 -- BP PLC prepared to purge the closed system on top of the deepwater Macondo wellhead while BP engineers and federal scientists continue to evaluate how to best complete a bottom kill on the well using a relief well, officials said.
A closed system was established July 15 with the installation of a capping stack. A transition spool sits between the failed Deepwater Horizon blowout preventer and the capping stack. An Apr. 20 blowout of the Macondo well resulted in a fire and explosion on Transocean Ltd.’s Deepwater Horizon, killing 11 people.
National Incident Commander and retired US Coast Guard Adm. Thad Allen said spill response crews are concerned that pressure could build in the Macondo annulus when heavy drilling fluid and cement is pumped into it for the bottom kill procedure. The concern is whether the transition spool could withstand that anticipated pressure.
Transocean’s Discoverer Enterprise drillship was being positioned on Mississippi Canyon Block 252. The Enterprise and the Helix Q4000 multiservice vessel will purge the closed system before more ambient pressure testing is conducted.
Another BOP was being brought to the scene in case engineers and scientists decide to replace the failed Deepwater Horizon BOP before the relief well is completed. In addition, they are evaluating a second option, which would involve building a pressure relief system at the top of the Macondo well, Allen said.
At some point, the Deepwater Horizon BOP will be removed for examination by investigators looking into the cause of the accident. Allen said scientists and engineers are trying to decide whether to remove the failed BOP before or after the bottom kill.
Jane Lubchenco, administrator of the National Oceanic and Atmospheric Administration, joined Allen and biologists in Cedar Key, Fla., on Aug. 18 to release 23 Kemp’s ridley sea turtles into the gulf. The turtles were rescued and rehabilitated from the oil spill.
As of Aug. 18, about 500 live turtles have been rescued during the oil spill of which more than 450 stranded or captured turtles had visible evidence of external oil. Some 350 turtles remained in rehabilitation facilities.
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BP, scientists plan system purge, pressure tests